Once your program is written and compiled, next concern is flashing and running on real device. Any programmer adapter dos this job quickly. But what if you don’t have adapter or you are lost in the island with attiny13 in your hands… then you can program chip manually. With some knowledge and patience you can do this with couple buttons.
As you may know avr microcontrollers are programmed through SPI interface. It consists of four wires – reset, MOSI, MISO and SCK. So all we need is to control these signals manually. Manually keying it is possible to program chip bit by bit. SPI programming speed isn’t limited towards slow. With buttons connected to these wires bits can be clocked in. As example a successful blinking LED program was programmed in to Attiny13 that way. It took 425 button clicks to do that. Here is a translated version of post.